The present invention relates to an apparatus for changing rotational speed with the aid of clutching activity of the type including a planetary gearing mechanism.
The above-mentioned type of apparatus having a planetary gearing mechanism incorporated therein is hitherto known and it is generally constructed such that an inner ring gear is rotatably supported in the planetary gearing mechanism located between an input shaft and an output shaft and a hydraulic cylinder is mounted to come in operative contact with the inner ring gear. When it is actuated, the inner ring gear is braked and thereby power transmission is accomplished between both the input and output shafts. On the other hand, while the hydraulic cylinder is inoperative, the inner ring gear is not braked and thereby power transmission is interrupted therebetween.
To rotatably support the inner ring gear in operative association with the input shaft or output shaft, the conventional apparatus as constructed in the above-described manner has an arm or the like holding means incorporated therein. However, the arrangement of an arm or the like holding means made in that way so as to hold the inner ring gear on the input shaft or output shaft requires an additional space in which the arm or the like means is to be housed, causing the whole apparatus to be designed and constructed in larger dimensions. In addition, the apparatus becomes complicated in structure which makes it very difficult to perform maintenance services.
To brake the inner ring gear a high intensity of thrust force is usually required. To this end a conventional hydraulic cylinder or a ring-shaped hydraulic cylinder having the same dimensions as those of the inner ring gear to be braked is employed for generating a required intensity of thrust force but due to the mounting of the above-mentioned hydraulic cylinder the apparatus is unavoidably designed and constructed in larger dimensions and becomes more complicated.